A friend of mine emailed last week to say that his small police department in Ohio was switching from the .40-cal pistols they’ve been carrying for years to a new 9mm. Just yesterday, local papers in South Dakota announced that the Sioux Falls PD was also switching from .40 to 9mm.

Quieter and still happening behind the scenes, two major federal agencies are both considering a move from their current sidearms to 9mm. Between the two they represent almost 20,000 armed personnel.

It’s a growing trend and, in my opinion, one that is long overdue.

Look at the photo (left). Even from just arm’s length away it’s hard to discern any real difference between the huge .45 Auto on the left and the tiny 9×19 on the right compared to something like a Surefire 6Z flashlight. (kids, that’s a flashlight the dinosaurs used to hunt cavemen during the Cantakerous Era)

The huge shift in American law enforcement to the .40 S&W in the mid-90s is often seen as proof that it’s more effective at stopping bad people from doing bad things. But that’s not how the .40 proliferated so quickly among LE agencies. The .40 S&W’s popularity is owed almost completely to the 1994 Assault Weapons Ban and its limitation on magazine capacity.

<Archer voice> Gasp you should! </voice>

The AWB allowed gun manufacturers to buy back previously issued LE magazines and resell them on the commercial market. That made all those used, abused, high capacity magazines worth their weight in gold. So manufacturers went to agencies and offered to trade them, at no cost, new & improved big-caliber guns for their wimpy little 9mms. The agency got a new gun that fit in its current holsters, replacing old and sometimes completely worn out guns. The administrators and union leaders got to parade the new guns in front of the troops as proof that they were Doing Something Important. And the gun companies got a bunch of guns that they could refurbish for a few dollars and then sell for a small mint simply by supplying one of those pre-ban high capacity magazines in the box.

That’s not idle speculation. I worked for two different major handgun manufacturers during the AWB. That’s how business was done. It made the companies a lot of money and made the LE customers very happy. And in the process it brainwashed many people into thinking that somehow the 9mm was a spitball while the .40 was a cannonball.

Now, decades of experience have proven that no common law enforcement handgun round, whether it’s 9mm, .40, 357, or .45 rises to the mythical “one shot stop” level. With current technology, the hollowpoints being designed and manufactured by the major ammunition companies are all comparable to one another regardless of caliber. Heck, it’s a very poorly kept secret that the FBI considers its current 9mm duty ammo — issued primarily to shooters who cannot handle the .40 during qualification — more effective than the .45 ammo it issues its own SWAT personnel. Why? The 9mm round was developed just a couple years ago. The .45 round is from the mid-90’s. That’s how much JHP design has advanced in 20 years!

The move to 9mm does many things for an agency. First, as alluded to above, it is easier for many marginal shooters to qualify with the lighter recoiling 9mm. That means a lot to law enforcement agency administrators and legal counsel: fewer reshoots (costly in terms of ammo and manpower) and fewer failures (costly in terms of retraining and, all too often, lawsuits). Second, for a given gun the officers have more rounds on board while actually reducing weight.

Third and perhaps most importantly in an age of tax shortfalls and budget cuts, 9mm ammo is just plain cheap. I just got a quote on some .45 ammunition — straight from the same company and at the same price most LE agencies would pay — and compared to the same exact brand in 9mm it was sixty percent more expensive.

9mm: easy to shoot, effective, economical. And it even works in 1911’s.

Train hard & stay safe! ToddG

65 Responses to “9mm: Cool again?”

A car moving 2mph will knock over any steel target but certainly isnt a deadly missle. Momentum is a very poor measure of terminal effectiveness.

Isn’t momentum (velocity) just how a 9mm is making up for a lower mass? Increasing velocity increases the ft lbs of energy but does not increase mass.

I only used the steel plate example because the steel absorbs every bit of energy supplied by the bullet and reacts, ie falls over. Not enough energy and it doesn’t move. The steel plate is a fixed object that requires a certain amount of energy to move. It’s movement or lack thereof is an indicator of the energy being absorbed. (Simple physics that I don’t have the background to fully understand)

I understand that momentum may not count. But mass most certainly does. If it doesn’t what explains that a heavier projectile traveling slower penetrates deeper in ballistics gel? Just look at Kenny T’s post above, all the same bullet but the heavy one always went deeper. Especially after having to pass through something else.

By no means am I trying to say that a 45 is better just that mass may be more important than the standard tests indicate.

So mass is “more important,” in a sense, to momentum than it is to energy. Momentum is what knocks steel targets down. But it’s not a wounding mechanism. You can see this for yourself pretty easily. A 55gr 5.56mm projectile at 2,700fps has about the same momentum as a typical 147gr 9mm projectile but few people would say they’re equal in terms of terminal ballistics.

Tony — No. Momentum is what knocks a piece of steel down, basically. So assuming your steel is safe to shoot with a 55gr 2700fps round, it will be knocked over with the same “force” as a 147gr projectile moving at 1010fps. Neither will knock over a piece of steel that is set to fall only to a .45 (230gr at 850fps, say).

In shooting, momentum is measured by “power factor” which is simply mass (in grains) times velocity (in fps). So given p=mv, you get:

You have raised another question, Why does power factor seem to be a forgotten number when comparing defense rounds? I first learned about Power Factor at my IDPA matches but I have never seen it mentioned when discussing defense rounds or really any other type of round, only as a baseline at matches.

Wouldn’t it be a contributing factor to the effectiveness of a round in a defense situation?

Tony — See Marc’s comment above. Momentum (power factor) is not a wounding mechanism. That’s why no one knowledgeable discusses it as a measure of terminal performance. It’s only used in shooting games because it’s easy to measure and easy to calculate.

I have a question regarding the momentum and “knocking power”. As far as I understood from the discussion, 5,56 is able to knock the same steel plates that 9×19 knocks, due to having about the same momentum. If so, why the companies that are manufacturing steel targets divide them by calibers and pistol poppers usually can’t handle carbine and rifle cartridges?

Although momentum isn’t a wounding mechanism, it does affect penetration. I don’t believe the 12″ gel standard is detailed enough. We need to develop a standard to find the minimum momentum required to break bone and still penetrate 12″ into gel. Easier said than done because of varying bone densities and angle of entry.

My first gun was a P226 in 9mm, I let my father somehow talk me into “stepping it up” to a 229 DAK in .40 but found myself not being so proficient and went back to a 229 9mm. Price of ammo, proficiency, and a dislike of the DAK trigger swapped me back.